Carburetor



March 10, 1931. L, LE BRETON 1,796,154

CARBURETOR Filed Sept. 6, 1928 e ,J 70 Z .f 5

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15'` e n 7a Z Km/eff??? Patented Mar. 10, 1931 UNITED STATES LON LEBRETON, F LES LILAS, FRANCE CARBURETOR Application led September 8,1928, Serial No.

It has already been proposed, in carburetors for internal combustionengines, to subject the float feed tank to the suction or vacuumprevailing in the main suction pipe, but this arrangement affords only arelative compensation. In fact, the variations of the resulting Vacuum(consisting of the vacuum on the feeding nozzle, less the vacuum in thefloat chamber) will correspond only in an irregular manner to the.relation between air and fuel when the engine speed varies or when thebarometric pressure changes due to variations of altitude. The output ofthe feeding nozzle depends upon the variations of the said resultingvacuum (or suction) when the level becomes stationary in the tank andwhen the supplying needlev valve is closed, but if the speed of theengine increases, the level in the float chamber diminishes, and thusacts-through the medium of the float-to raise the said needle valve.

In this manner the conditions may be such at high speeds that the supplyof fuel to the float chamber will be just sufficient for the feed of thenozzle, so that the valve will be almost constantly raised from itsseat, and henceforward the correction due to the difference in thevacuum will no longer prevail, since the float feed chamber is inpermanent relation to the fuel recipient or intermediate chamber whichoperates at atmospheric pressure. i

The present invention relates to improvements in this type of carburetorwhereby the above-mentioned defects will be obviated. Such improvementsconsist essentially in the combination of a calibrated needle whichmodifies the feeding section for the fuel according to its ascent, andhence according to the output of the feeding nozzle which is placed'in arecipient subjected to the suction or vacuum and communicates with themain body of the carburetor, which recipient also communicates by acalibrated orifice with the upper space in the iioat tank, said tankbeing provided with an optionally adjustable atmospheric outlet.

In the appended diagrammatic drawing, B0 and by way of example:

304,312, and in France September 14, 1927.

Figs. 1 and 2 show two different constructional forms of the improveddevice according to the present invention.

The improved carburetor comprises, as in the known apparatus, a mainbody a whereof one end b is an atmospheric inlet and the other end c isconnected with the admission end of the engine. The said body a containsthe regulating element d, such as a throttle or the like closing means,the diffuser e and the sprayer f; the said sprayer is subjected to thesuction and is supplied by the float feed tank g by means of a submergednozzle h placed in the recipient or chamber z'.

According to the invention, the said recipient or chamber i is connectedat its upper part, by the calibrated orifice j, with the upper space inthe float feed tank g, this being connected with the exterior atmosphereby a calibrated orifice k, optionally adjustable. The said iioat feedtank g is supplied with fuel through an orifice whose section variesaccording to the variations in the suction (or vacuum) acting upon thesubmerged nozzle h. For this purpose, the valve rod Z comprises acontact portion which forms a valve member m, and is extended forinstance by a tapered needle a coacting with a calibrated orifice o, sothat the vertical movements of the rod Z, depending upon the variationsof level of the liquid, will produce corresponding displacements of theneedle a with reference to its coacting orifice o, and hence variationsof the flow section of the fuel.

In these conditions, when the engine operates, the vacuum acts upon thesubmerged nozzle h and upon the calibrated orifice y' which, as is wellknown, checks the feed of the fuel.

The apparatus is adjusted in such manner that when on the ground level,the calibrated orifice 7c will feed suicient fuel air to supply thecalibrated orifice y', so that the float feed tank g will not besubjected to the vacuum.

As the apparatus rises above the ground in an airplane or the like, thebarometric pressure will diminish. The calibrated orifice k no longerfeeds sucient air to supply the orifiee y' subjected to the suction, andthis will hence create a depression in the upper space 2 1,7ee,1e4

in the float chamber g and u on the surface of the liquid. The height othe column; of liquid which is to counterbalance this new state of thesuction will hence tend to increase, 5 and therefore to raise the floatand to lower the valve l. The needle n on t e end of sald rod willreduce the flow section at o, thus reducing the feed of fuel to thesubmerged nozzle h. The decrease in the output of said nozzle depends uon the increase in the height of the column o li uid above it, and henceupon the wei ht of said liquid. By suitably regulating tie calibratedorifices c and j, I thus provlde conditions in which the reduction ofthe weight of the liquid withdrawn, said reduction depending upon thebarometric pressue and hence upon the variations of altitu e.

The preceding arrangements are applicable to the known carburetors. Inthis case, it may happen that the floats p are too heavy, so that whenunder suction, the liquid will rise to the orifice j which then feedsthe fuel. Such defects can be obviated by placing between the top of theioat p and the pivoted arm r connecting it with the valve Z, a disc s,of determined size and weight, which is pivoted to the arm r, and thuswhen the level descends in the oat tank g, the float p is sepas0 ratedfrom said disk. Under the action of the vacuum (or suction which isantagonistic to its weght,) the said disc and with it the needle valve Zwill take a position of equilibrium. This represents in fact thecombination of the se float p serving for hydraulic equilibrium, with afiat member s serving for aerodynamic equilibrium. I claim:

A carburetor comprising a fuel chamber 40 having a lioat therein and airand fuel inlets, a need e valve for said fuel inlet controlled by saidfloat, an intermediate chamber disposed in said float chamber having aninlet to 'the fuel in said float chamber and an inlet to the air spaceabove said float in said float chamber, a spray nozzle from saidintermediate chamber extending into the fuel inlet pipe of the engine, asurface member cooperating withl said float for hydraulic regulation,said surface member which is subject to the variations of theaerodynamic pressure of the atmosphere of the tank being connected withthe pivoted arm controlling the needle valve and is subject to thehydrostatic impulsion of the float. v

In testimony whereof I aix my signature.

LEON vLE BRETON.

